Аннотация:It was previously found that the formation of the polymer chain in the hydrolytic polycondensation (HPC) of diorganodichlorosilanes passes with a great share stepwise assembly, but smaller blockwise (as gomorofunctional condensation (GMFC) of diorganosilandiols) . The reason of this is the nature of the heterophase process which define drawback hydrolyzing agent in the reaction zone and as a consequence, the assembly (forming) of the chain passes through "connection" to the growing chain both monomer molecules R2SiCl2 and intermediate R2SiClOH.
The comparative data was given about the assembly of polymer chain for four monomers classes such as Me2Si(OH)2, Me2SiX2 (X = Cl, OR (R = Me, Et, iPr, Bu), OCOCH3). This objective was solved by studying the composition of products in the hydrolysis diorganodialkoksisilanes depending on the ratio of reactants. The main tool for the analysis and evaluation criterion in the oligomer chain was the dependence conversion of the monomer (Xm) vs the conversion of the functional group (Xf)1. The GLC method was used to estimate composition of products and nature of chain.
The dependencies of monomer conversion vs functional groups conversion were obtained on the basis of data about the composition of products GMFC Me2Si(OH)2, HPC Me2SiX2. It was established that the share of stepwise assembly oligomeric molecules and the contribution heterofunctional condensation in chain growth rise in a series of reactivity increasing Me2Si(OH)2 < Me2Si(OR)2 < Me2Si(OCOCH3)2 ≈ Me2SiCl2. The dependencies shift Xm = f(Xf) from left to right is usually associated with an increase in the reactivity of the oligomers2. We assume that such series of dependencies may be caused by the change in the ratio of the velocities of mass-transfer and chemical reactions, defining a different intensity of "feeding" reaction phase by the water.